the PSU is massive overkill, a vx550 would suffice and still have plenty of headroom.
i personally wouldn;t get a 'green' HDD. but thats a perosnal choice, i'd want more performance. are you specifically looking for a green drive?
what are you planning on doing with this rig? I'm wondering if the 9400gt is a good choice. obviously its not going to game well, but if you are in it for productivity a 5 series card from ATI may be a better choice (offering 3 monitors form a single card if you ever need it)
I'm actually building the computer for a cousin of mine who wanted a to get a new computer since he started college. I chose the green because it's 2TB version is a lot cheaper than the 2TB version of the caviar black but I think I'm just gonna let him choose between that and the black 1TB version, and he can just buy an external hard drive when he get's more money. I think he just want's the computer for graphic design programs and stuff like that.